1. For the complex [CrF6]3– the peak maxima in the UV-Vis spectra are found at 275, 427, and 638 nm with absorption coefficients between 10 and 100 M–1cm–1 while for [VF6]4– the peak maxima are found at 464, 512, and 953 nm with similar absorption coefficients. Find B and 10Dq for each complex. Predict the spin-only magnetic moment for the two complexes. Which of these metals is lower on the Irving-Williams series and which is higher? The g-value for [CrF6]3– was found to be 1.98. Estimate the spin-orbit coupling constant. Would you expect splitting , shoulders, or observable spin-forbidden transitions in the [CrF6]3– optical spectrum? Why or why not? Hint: The spin-orbit coupling constant in Cr3+(g) is 275 cm–1.
2. For the reaction [Co(NH3)5(H2O)]3+ + X– → [Co(NH3)5X]2+ the rate constants for X– = Cl–, Br–, N3–, and SCN– are all similar, differing by less than a factor of 2. What does this suggest about the mechanism of the substitution? Would you expect the equilibrium constants for these reactions to be less than 1 or greater than 1. Briefly explain. SCN– is ambidentate: which atom do you think is bonding to the metal in this reaction? Briefly explain. Based on this data, is N3– a weak ligand or a strong ligand. Briefly explain.
3. Using [PtCl4]2– (D4h) as a starting material, design syntheses for cis-[PtCl2(NO2)(NH3)]– and trans-[PtCl2(NO2)(NH3)]–.
4. Are the following complexes stable by the EAN rule? Why or why not? [V(CO)6], [Cr(η6-C6H6)2], trans-[Ir(CO)Cl(P(C6H5)3)2] (Vaska’s complex), [Ni(η4-COD)2] (COD = 1,5-cyclooctadiene). Which, if any, of these complexes might be considered as a catalyst for alkene hydrogenation or hydroformulation? Briefly explain.
5. Briefly explain why the nanoparticles of a metal are usually superior to the bulk metal when used as a catalyst in reduction reactions.